This invention relates to geminal dinitro compounds and in particular to a process for preparing the same.
Many geminal dinitro compounds have found application in the production of energetic materials. 2,2-dinitropropanol (DNPOH) is useful in the production of two energetic plasticizers: bis(2,2-dinitropropyl)formal (BDNPF) and bis(2,2-dinitropropyl)acetal (BDNPA). 2,2-dinitropropanediol is useful in the synthesis of nitro-containing polymers, explosives and various other nitro-containing organic compositions.
Heretofore, the most general method for preparing .alpha.,.alpha.-dinitro compounds has been that of Shechter et al, U.S. Pat. No. 2,997,504, in which treatment of the nitronate salt of a primary or secondary nitroparaffin with silver nitrate and an inorganic nitrite in aqueous media gives the corresponding gem-dinitro compound and metallic silver. The major drawback of this method is its use of silver nitrate. Even though the metallic silver can be recovered and easily converted to silver nitrate, experience has shown that silver losses average about 1%. Such loss represents a serious economic disadvantage. Another economic disadvantage is that the process requires the use of expensive low-chloride grade sodium hydroxide to avoid formation of silver chloride.
Kornblum et al, "Oxidative Substitution of Nitroparaffin Salts", J. Org. Chem., 1983, 48, 332-337, report that in 1979 Matacz et al reported that aqueous potassium ferricyanide is a useful reagent for oxidatively substituting secondary nitroparaffin salts, but that with the salts of primary nitro compounds this reagent fails. Kornblum et al report yields of about 60 to 90% using the method of Matacz et al for the preparation of .alpha.,.alpha.-dinitro compounds, .alpha.-nitro sulfones, and .alpha.-nitro nitriles. One disadvantage of this method is the significant quantity of the ferricyanide employed. Kornblum et al employ potassium ferricyanide in amounts ranging from about 250 mol% to about 1000 mol%, based upon the amount of the nitroparaffin starting material. In a large scale process this amount of potassium ferricyanide represents a significant economic impact, even though the potassium ferricyanide is less expensive than silver and nitric acid or silver nitrate. Additionally, this amount of potassium ferricyanide represents a significant problem of disposal.
We have found that the amount of ferricyanide required for synthesis of geminal dinitro compounds can be reduced to a catalytic amount. We have also found that potassium ferricyanide can be employed as a catalyst for the synthesis of functional geminal dinitro compounds, such as alcohols and esters and also for the synthesis of terminal geminal dinitro derivatives.
Accordingly, it is an object of the present invention to provide a process for preparing geminal dinitro compounds.
It is another object of the present invention to provide a process for preparing functional geminal dinitro compounds.
Other objects, aspects and advantages of the present invention will be apparent to those skilled in the art.